1 (often the Sabbath) a day of religious observance and abstinence from work, kept by Jews from Friday evening to Saturday evening, and by most Christians on Sunday: [as modifier]:sabbath candlessabbath law
2 (also witches' sabbath) a supposed midnight meeting held by witches.
Old English, from Latin sabbatum, via Greek from Hebrew šabbāṯ, from šāḇaṯ 'to rest'
sabbath in other Oxford dictionaries
Definition of sabbath in the US English dictionary